Recently, as energy consumption is increased, a solar cell has been developed to convert solar energy into electrical energy.
In particular, a CIGS-based solar cell, which is a P-N hetero junction apparatus having a substrate structure including a glass substrate, a metallic back electrode layer, a P type CIGS-based light absorbing layer, a high resistance buffer layer, and an N type window layer, has been extensively used.
In addition, in order to increase the efficiency of the solar cell, various studies have been performed.
According to the above solar cell of the related art, since the solar cell is installed in the form of a plane, when the solar light is irradiated into the solar cell at a right angle, light collecting efficiency of the solar cell is increased. In contrast, when the solar light is irradiated into the lateral side of the solar cell, the light collecting efficiency of the solar cell is rapidly reduced. In addition, when the solar light is irradiated into the lateral side of the solar cell, the solar light is reflected from the solar cell installed in the form of the plane, so that the solar light cannot be effectively utilized. Since the solar cell is a technology having the infinite possibility of development as future fuel, the solar cell must be urgently developed.